Typically when a country is facing a sovereign debt crisis, it can devalue its own currency to make its goods more attractive in export markets and perhaps lower its debt burden.

But the shared euro has prevented Greece and other troubled European economies such as Portugal, Ireland, Italy and Spain from turning to devaluation. It's also one of the reasons the richer European countries such as Germany and France are scrambling to prevent a Greek default.

Default speculation has led to fears that the eurozone will break apart. But economists say the barriers to exiting the euro are too significant to make it a viable option, even with a looming default.

"The benefit of leaving the eurozone is simply not strong enough for a country to leave," said Russell Price, senior economist for Ameriprise Financial.

Jay Bryson, international economist for Wells Fargo Securities, said it's tough to project what will happen with the euro membership five or more years from now. But he sees little chance of anyone dropping the euro anytime soon.

"The barriers to doing it are very, very high," said Bryson. "Germany and France can't kick Greece out, as much as they might like to. And it would be difficult for Greece to leave on its own. It would likely have to leave the European Union, and that would take a unanimous vote of the entire EU."

If such an exit were to happen, Greek consumers and businesses would probably transfer their cash to other European banks in order to protect its value, causing a collapse of the Greek banking system and likely the nation's economy.

But some economists argue the imbalances within the eurozone can't be sustained forever.

"The only way it stays together is a long-term wealth transfer from the north to south that goes on for a long time. I don't believe the Germans are willing to do that," said Bill Watkins of the Center for Economic Research and Forecasting.

"We've already seen the disruptions and social unrest," Watkins said. "I think eventually the people of Greece, Spain, Italy and the rest are going to demand that their government uses all the tools other countries have available to them, and that includes devaluation."

But economists are expecting the European debt crisis to get worse before there's a resolution. And they also expect the impact of the crisis to be felt by the U.S. economy.

Two-thirds of those surveyed say a Greek default would have either a severe or significant impact on the United States, with only two calling the impact "mild."

"The risk of financial contagion from Europe's debt crisis could be the one shock that tips the U.S. back into recession," said Sal Guatieri, senior economist with BMO Capital Markets.